Conventionally, a thermal-type air flow measuring device for measuring an air flow rate by use of heat transfer between the device and air is widely known. For example, the air flow measuring device is disposed in an intake passage to an internal combustion engine and used for measuring a flow rate of intake air suctioned into the engine. The conventional air flow measuring device takes in a part of air flowing through a predetermined passage, and generates an electrical signal that is in accordance with a flow rate of air in the passage. For example, the conventional device includes the following configuration.
The air flow measuring device includes a housing that defines a bypass flow passage through which the taken-in air passes, a sensor that is accommodated in the bypass flow passage to produce the electrical signal as a result of a heat transfer between the sensor and the taken-in air, a terminal for outputting the electrical signal produced by the sensor to the outside of the device, and a conduction member including a terminal for supplying electric power to the sensor. The sensor is assembled with a processing part that performs predetermined processing on the generated electrical signal thereby to constitute a plate-like sensor assy. The sensor assy is held by the housing such that the sensor projects into the bypass flow passage.
The conventional air flow measuring device is obtained by providing beforehand through insert-molding a molded product having a conduction member (hereinafter referred to as a “molded product with a terminal”), and by injection-molding a secondary molded part, with the molded product with the terminal and the housing which holds the sensor assy as insertion items. For this reason, since the conventional air flow measuring device is provided through at least two insert-moldings, its manufacturing process is complicated, and simplification of the manufacturing process is required.
For a molding method for the conventional molded product with the terminal, in order to avoid cumbersomeness of directly setting a terminal piece as the conduction member in a die, a method whereby a holding member, which has been shaped, is made to hold a terminal piece in advance and the holding member holding the terminal piece is set in a die as the insertion item to provide the molded product with the terminal through insert-molding, is widely known (see, for example, JP-A-H07-142145). However, the providing of the molded product with the terminal by insert-molding is still the same. Thus, the complicatedness of the manufacturing process of the air flow measuring device may not change very much.